What causes cluster headaches?

Cluster headaches do not appear to be related to other illnesses or to diseases of the brain.

Some of the triggers of cluster headaches include:

Taking certain medications (such as nitroglycerin)

Heavy smoking

Drinking alcohol

An interruption in your normal sleep pattern

Abnormal levels of certain hormones

Problems with the hypothalamus, which controls your body's "biological clock"

What causes rebound headache?

Prescription and over-the-counter medicine for migraines (such as aspirin and acetaminophen) can cause rebound headaches if you take them too often. If you get rebound headaches, these medicines should not be taken more than 2 days per week. Sedatives, tranquilizers and ergotamine medicines also can cause rebound headaches. Talk with your doctor to find out if you should stop taking these medicines or should take less of them.